The use of corticosteroids during pregnancy does not appear to increase the risk of a baby being born with an orofacial cleft, the results of a new study indicate.

Orofacial clefts are birth defects in which there is an opening in the lip and/or palate (roof of the mouth) that is caused by incomplete development during early foetal formation. According to the Cleft Lip and Palate Association of Ireland, one in every 700 babies born in Ireland has a cleft.

Corticosteroids are used for asthma, allergies, eczema, psoriasis, autoimmune diseases and cancer. Use of corticosteroids during pregnancy has been associated with orofacial clefts in animals and similar risks in humans are suspected.

Danish researchers looked at data on 832,636 live births which took place between January 1996 and September 2008. Of these, one in five women used corticosteroids once or more in the four weeks before pregnancy up to the birth of their baby.

The most common were dermatological (skin) corticosteroids (43.3%), other topical solutions (e.g. eye drops or ear drops), nasal sprays (21.6%), inhalants, (14.3%) and oral medications (4.2%).

The researchers subsequently identified 1,232 orofacial clefts in infants up to 12 months of age.

"Women who used any corticosteroid during the first trimester were not significantly more likely to bear offspring with a cleft lip, with or without a cleft palate, or a cleft palate alone, than women who did not use any corticosteroid during the first trimester," the researchers explained.

They did find that the use of dermatologic corticosteroids was associated with an increased risk of cleft lip with or without cleft palate, however oral medications, inhalants, nasal sprays and other topical corticosteroids did not increase the risk.

This suggests that the association may therefore be from multiple statistical comparisons rather than causality.

"Our results add to the safety information for a class of drugs commonly used during pregnancy," the team said.

However, it cautioned that while the apparent lack of an association in this study supports the theory that moderate to strong risks are unlikely, it does not prove that corticosteroids are completely safe.

Details of these findings are published in the Canadian Medical Association Journal.

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